Exponential Growth of System Complexity

Software complexity in aerospace systems is increasing exponentially. Source lines of code (SLOC) in aircraft is doubling about every four years. That trend has been in place for at least five decades and applies to both commercial and to military aircraft.

Since development costs for software systems increase exponentially with SLOC, costs are increasing at an alarming rate.

Examples

The A-310 was introduced in 1983. Five years later, the A-320 had twice the on-board SLOC requiring an estimated 2.14 times the development effort. Five years later the A-330 had 2.5 times more on-board SLOC than the A-230 and required an estimated 2.7 times the development effort.
The B-757 was first flown in 1982. Five years later, the B-737-400 had 1.9 times the on-board SLOC requiring an estimated 2.7 times the development effort. In another five years the B-777 had 21 times more on-board SLOC than the B-757 and required an estimated 28.5 times the development effort.

The F-16 was first flown in 1974. Twenty years later, the F-22 had 126 times the on-board SLOC requiring an estimated 204 times the development effort. The F-35, first flown in late 2006 had 1.4 times the on-board of the F-22 and 177 times that on the F-16. The F-35 software development effort was an estimated 1.5 times greater than the F-22 and 298 times greater than the F-16.

Estimated software development cost increased by a factor of almost 300 over a 32 year period.